A study of the role and function of deoxysugars is carried out using two complementary approaches: 1) A detailed study of individual enzymes involved in the metablism of deoxysugars. A. Thymidine diaphosphoglucose -4,6- hydrolase the enzyme that initiates 6-deoxyhexose biosynthesis will be studied to understand better structure and function of "half of the site" ezymes. B. Comparative studies will be carried out on UDP-galactose 4-epimerase, another "half of the site" enzyme. C. Bacteral neuraminidase and its role on the removal of sialic acid (5-N-acetylamino -3.5-dideoxy D-glycero-D-galacto-nonulosonic acid) from host tissue is examined. 2. Changes of peripheral deoxysugars composition will be related to cell surface phenomena such as immuno-response and ability to agglutinate.